title: Aggressive mature natural killer cell neoplasms: from epidemiology to diagnosis.
abstract: Mature natural killer (NK) cell neoplasms are classified by the World Health Organization into NK/T cell lymphoma, nasal type (NKTCL), aggressive NK-cell leukemia (ANKCL) and chronic lymphoproliferative disorders of NK-cells, the latter being considered provisionally. NKTCL and ANKCL are rare diseases, with higher prevalence in Asia, Central and South America. Most NKTCL present extranodal, as a destructive tumor affecting the nose and upper aerodigestive tract (nasal NKTCL) or any organ or tissue (extranasal NKTCL) whereas ANKCL manifests as a systemic disease with multiorgan involvement and naturally evolutes to death in a few weeks. The histopathological hallmark of these aggressive NK-cell tumors is a polymorphic neoplastic infiltrate with angiocentricity, angiodestruction and tissue necrosis. The tumor cells have cytoplasmatic azurophilic granules and usually show a CD45(+bright), CD2(+), sCD3(-), cytCD3epsilon(+), CD56(+bright), CD16(−/+), cytotoxic granules molecules(+) phenotype. T-cell receptor genes are in germ-line configuration. Epstein-Barr virus (EBV) -encoded membrane proteins and early region EBV RNA are usually detected on lymphoma cells, with a pattern suggestive of a latent viral infection type II. Complex chromosomal abnormalities are frequent and loss of chromosomes 6q, 11q, 13q, and 17p are recurrent aberrations. The rarity of the NK-cell tumors limits our ability to standardize the procedures for the diagnosis and clinical management and efforts should be made to encourage multi-institutional registries.
authors.affiliation: Department of Hematology, Laboratory of Cytometry, Hospital de Santo António, Centro Hospitalar do Porto, Rua D. Manuel II, s/n, 4099-001, Porto, Portugal. mmc.lima@clix.pt
authors.forename: Margarida
authors.initials: M
authors.lastname: Lima
mesh_terms: D001208:Asia / Q000453:epidemiology; D004854:Herpesvirus 4, Human / Q000302:isolation & purification; D006801:Humans; D007694:Killer Cells, Natural / Q000378:metabolism / Q000473:pathology*; D007938:Leukemia / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology / Q000821:virology; D054391:Lymphoma, Extranodal NK-T-Cell / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology / Q000821:virology; D009669:Nose Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology / Q000821:virology; D015995:Prevalence; D013020:South America